Many modern computing devices include multiple wireless subsystems, which may also be referred to as radios or collectively as wireless circuitry herein. A computing device can use the wireless circuitry to communicate concurrently via multiple wireless communication technologies. In many instances, wireless communication technologies used by the computing device use frequency channel bands (sets of radio frequencies) that may interfere with each other. In such instances, energy used by one wireless subsystem in a particular frequency channel band can leak into an overlapping, adjacent, or non-overlapping distant frequency channel band used by another wireless subsystem in the same computing device. This energy leakage can raise the noise floor for receive signal chains of the wireless circuitry, can cause a problem known as “desense,” and can affect the performance of wireless communication through the wireless circuitry. In many instances, radio frequency interference from co-located wireless subsystems or from wired connection ports can negatively impact the use of certain radio frequency channel bands and, in severe cases, can render certain radio frequency channel bands unusable. Accordingly, wireless radio frequency interference that can result in desense poses a problem for in-device coexistence of multiple wireless subsystems that use different wireless communication technologies.
In a representative scenario, one wireless subsystem can emit a transmission via a first wireless communication technology, which can be referred to as an aggressor wireless communication technology, or aggressor technology, while another wireless subsystem can receive data via a second wireless communication technology, which can be referred to as a victim wireless communication technology, or victim technology. Data reception via the victim technology can be impacted by the aggressor transmission, particularly in instances in which the wireless subsystem using the aggressor technology uses a relatively high transmission power. In this regard, received packet errors in received signals, or even complete deafening of a receiver that uses the victim wireless subsystem access technology can result from radio frequency interference that can be caused by the co-located aggressor technology transmission. For example, simultaneous radio frequency transmissions by a wireless personal area network (WPAN) signal from a first wireless subsystem operating in a computing device while also receiving radio frequency signals of a wireless local area network (WLAN) signal via a second wireless subsystem on the computing device can impact the performance of the second wireless subsystem, e.g., causing errors or unstable connections. Additionally, computing devices can include high-speed wired connection points, and in some instances, interfering radio frequency energy can be emitted by an active high-speed wired connection port that can result in errors in the transmission and/or reception of wireless signals, e.g., via a WLAN or WPAN connection. Representative wireless connections can include those that operate in accordance with an IEEE 802.11 Wi-Fi communication protocol or a Bluetooth communication protocol. Representative wired connection ports (and associated connected devices) can include those that operate in accordance with a universal serial bus (USB) communication protocol. Radio frequency interference received by a wireless subsystem from a co-located wireless subsystem or received from radio frequency energy radiated by a wired connection port in the same computing device shall be referred to herein as coexistence radio frequency interference, or coexistence interference for short. Methods and apparatus to mitigate coexistence interference and improve performance of wireless subsystems in a computing device are further described in detail herein.